<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    //冒泡  从小到大  具体到详细    往外散开
    //捕获  反着来
    事件监听{
        element.addEventListener(event, function(){}, boolean);
                                事件类型  函数[激活后怎么做]  何时执行{ false[默认] 冒泡 true 捕获}
    }


</body>
</html>